1. Field of the Invention
The present invention is related to systems for measuring liquid levels within liquid storage tanks and more specifically to systems to electrically measure the quantity of fuel remaining in a vehicular fuel tank.
2. Description of the Prior Art
Although many techniques have been disclosed which could be used to measure the liquid levels in storage tanks, the most commonly used system for measuring fuel level in the fuel tank of a motor vehicle, employs a variable resistor within the tank. The wiper arm of the variable resistor is connected through a pivot to a float which monitors the upper level of the fuel in the tank. Of course, whenever the vehicle is traveling on a grade, the fuel level is shifted at an angle to the normally horizontal reference plane of the fuel tank and causes the float to monitor an erroneous level, either higher or lower than the correct level. Additionally, when the vehicle starts or stops its motion, waves are generated in the stored fuel. This is commonly referred to as "sloshing" and causes the float to responsively bounce up and down, thereby effecting the measurement readings. Mechanical and electrical damping techniques have been employed to reduce the effects of fuel level shift and sloshing. However, they have not been shown to be suitable for obtaining instantaneous and accurate fuel level measurements.